Centralizers



y 1965 D. F. SAURENMAN 3,196,951

CENTRALIZERS Filed April 30, 1962 flea/7 F. Jae/@0070 INV EN TOR.

ATTORNEY United States Patent berger Well Surveying Corporation, Houston, Tex., a corporation of Texas Filed Apr. 30, 1962, Ser. No. 191,016 8 Claims. (Cl. 166-241) This invention relates to apparatus for centralizing a tool in a well bore and more particularly to a spring type of centralizer which centralizes by a combination of bending and torsion of its spring members which operate in a spiral or warp-around manner relative to the tool rather than by bending of spring members in planes radial to the tool, thus resulting in considerable reduction of length.

An increasing problem with well tools used in subsurface logging of well bores is the length of the tool. A considerable number of tools such as sonic logging tools, perforating equipment, etc., require centralization. Centralizers for this purpose generally consist of bow or leaf type springs which require considerable length to obtain satisfactory centering forces over a range of borehole or casing sizes.

Accordingly, it is an object of the present invention to provide a new and improved centralizer of short length and operable over a range of borehole or casing sizes.

Appartus in accordance with the present invention includes a plurality of wire members equidistantly spaced about the periphery of a support, each of the wire members having end portions extending generally perpendicular to the axis of the support and tangential to the support so that the wires are tangentially extended relative to the body. The tangential extension permits the wire members to centralize by the inherent restraining force in the wire members when they are flexed at their end portions.

The novel features of the present invention areset forth with particularity in the appended claims. The present invention, both as to its organization and manner of operation together with further objects and advantages thereof, may best be understood by way of illustration and example of certain embodiments when taken in conjunction with the accompanying drawings in which:

FIG. 1 is a view in partial elevation and partial crosssection of apparatus illustrating the present invention;

FIG. 2 is a partial view in cross-section of apparatus illustrating a step in assembling the apparatus; and

FIG. 3 is an enlarged view in cross-section taken along line 3-3 of FIG. 2. 7

Referring now to FIG. 1, a part of a cylindrically shaped housing 10 is shown which may be part of a tool suitable for use in a well bore. A centralizer 11 embodying the present invention is mounted on the housing It) and is comprised generally of a tubular sleeve member 12 upon which a number of bowed wire members 13 are mounted about the periphery of the sleeve member. The tubular sleeve member 12 has a uniform bore 44 therethrough sized to beslidably positioned on the housing 19 and fixed against relatively longitudinal movement by upper and lower 'stop collars 15, 16 which are held in position by snap rings 17 received in grooves in the housing. The sleeve member 12 is free to rotate relative to the housing between the stop collars 15, 16.

The tubular sleeve member 12 has enlarged upper and lower end portions 18, 19 spaced from one another by a thin wall connecting section. The end portions 18, 19 respectively have internal annular recesses or grooves 213, 21. Equidistantly spaced about the outer periphery of the enlarged end portions of the sleeve member are elongated slots 23, eight such slots being shown, although this number may be varied. The slots 23 open towards the center of the sleeve 12 and are deep enough to open to "ice the internal annular recesses 20, 21 in the sleeve member 12. Each of the slots 23 is similarly inclined at an angle of about 30 degrees relative to a central axis of the sleeve 12. The slots in the upper end portion 18 and the lower end portion 19 are complementarily arranged with opposite directions of inclination so that an imaginary extension of the slots would terminate at an apex midway of the length of the sleeve 12.

The wire members 13 have an arcuate curvature over a distance as long as the spacing between the slots 23 in the end portions 18, 19 of the sleeve and have relatively short end sections 24 arranged parallel to one another. The short end sections 24 are also curved slightly to conform to the curvature of the housing 10 when disposed in the annular recess at 20, 21 in the sleeve member. The end sections 24 also may be offset as shown by numeral 26 (FIG. 3) to hold the wire members in the sleeve when assembled.

The centralizer 11 may be assembled by inserting the end sections 24 of a wire member 13 through longitudinally aligned pair of slots 23, that is, one section 24 inserted in the upper enlarged portion 18 and one end section 24 inserted in the lower enlarged portion 19. The wire member 13 is then turned or rotated until the end sections 24 lie within the annular recess and the arcuate section of the wire members lie in the slots 23. At this time the wire member 13 is generally tangent to the curvature of the sleeve and the offset 26 holds the wire member in the sleeve. This procedure is repeated for the insertion of each wire member 13 until all the wire members are disposed in the sleeve. Then the entire assembly is slid onto the body 19 and attached in place by the annular stop rings 15, 16 and snap rings 17.

In another embmodiment of the present invention, the wire members 13 can be removed or inserted without removing the sleeve member 12 from the tubular housing body 16. As shown in FIGS. 2 and 3, upper and lower parallel slots 28, 29 are provided in the outer periphery of the housing 10. The spacing between the upper and lower housing slots 28, 29 is the same as the spacing between the ends 24 of a wire member; however, the location of the slots 28, 29 relative to the grooves for the locking rings 17 is dissimilar for reasons which will hereafter be more apparent.

To assemble the wire members on the body 10, sleeve 12 is positioned on body 10 with the annular recesses 20, 21 in registry with the respective slots 28, 29. The end portions 24 of a wire member 13 are then inserted through the slots 23 in he upper and lower enlarged end portions of the sleeve and extend into the slots 28, 29 provided in the outer periphery of the housing. The wire member is then turned or rotated until the end portions 24 abut the annular recesses in the sleeve and the arcuate section of the wire members lies in the slots of the sleeve. Slot 28, 29 is, of course, long enough to permit such rotation. This procedure is repeated for the insertion of each of the wire members until all the wire members are disposed in the sleeve. It will be readily appreciated that the wire members 13 may be individually replaced, removed or inserted in this manner without removal of the sleeve from the housing. After the wire members are mounted in the sleeve, the sleeve is shifted displacing the annular recesses from registry with the slots in the housing thereby locking the ends of the wire members between the sleeve and housing. The sleeve is then locked in position by the snap rings received in the grooves.

A corollary centralizer arrangement would be the substitution of flat sheets of any suitable spring material for the springs 13, such sheets being suitably attached to a body and being transposed about that body in a tangential configuration identical or similar to the springs 13 shown in FIG. 3. Various suitable mechanical attachments between the fiat sheet springs and the body (similar to 12) are feasible and easily accomplished by anyone familiar with the art.

In operation, the wire members 13 will center the tool on which such centralizers are mounted by contact of the spring members 13 with the. wall of the well bore and by their inherent resistance to deformation, it being noted that the resistance increases with increased deformation. In practice the free location or position of the extremities of the spring members 13 should encompass a circumferential area greater than the cross-sectional area of the Well bore. All spring members 13 will be deformed and those suffering greatest deformation will have greatest resistance to deformation, such resistance providing the force to act on the tool to center it in the well bore. In the ideal or preferred state, the tool would be maintained exactly in the center of the well bore. In this case, all spring members 13 would be equally deformed and would have equal resistances to deformation. Thus, equal forces act on the tool to remain exactly in the center of the well bore. Any movement of the tool from the center of the well bore will vary the spring deformations creating greater spring forces on the side of the tool nearest the well bore wall and lesser spring forces on the side of the tool farthest from the well bore wall, such unbalanced forces tending to move the tool back to the center of the well bore.

While particular embodiments of the present invention have been shown and described, it is apparent that changes and modifications may be made without departing from this invention in its broader aspects and, therefore, the aim in the appended claims is to cover all such changes and modifications as fall within the true spirit and scope of this invention.

What is claimed is:

1. A centralizer for use in a well bore comprising a cylindrical support member, spring members individually having a configuration which lies in a single plane and having attaching portions for positioning said spring members about the periphery of said support member, said attaching portions being integrally formed on said spring members for normally extending the planes of said spring members tangentially to said support member to achieve centralizing forces by a combination of bending and torsion of said spring members, and means spaced from said support member for loosely holding said attaching portions between said spaced means and said support members with said spring members tangential to said support member.

2. A centralizer for use in a Well bore comprising a cylindrical body, a tubular sleeve received on said body; at least part of said tubular sleeve spaced from said body;

a plurality of spring members in the form of arcuately curved wires with terminal ends; means forming a part of said terminal ends for loosely positioning said terminal ends between said cylindrical body and said spaced part of said tubular sleeve at equidistant spacings about the periphery of said sleeve to project the arcuately curved portions of said spring members in tangential planes relative to said sleeve.

3. A centralizer for use in a Well bore comprising a cylindrical body, a tubular sleeve received on said body and having spaced end portions; a plurality of spring members in the form of arcuately curved wires with terminal ends; means for positioning said terminal ends between said cylindrical body and said tubular sleeve to project the arcuately curved portions of said spring members in tangential planes relative to said sleeve, said positioning means including slots in said end portions equidistantly spaced about the periphery of said sleeve and an internal annular groove in said end portions opening to said slots whereby said terminal ends are received in said annular groove and portions of said wires lie in said slots.

4. A centralizer for use in a well bore comprising a cylindrical body, a tubular sleeve slidably received on said body and having spaced end portions; means to lock said tubular sleeve on said body against longitudinal movement; a plurality of spring members in the form of arcuately curved wires with terminal ends; means for positioning said terminal ends in said tubular sleeve to project the arcuately curved portions of said spring members in tangential planes relative to said sleeve, said positioning means including slot in said end portions, equidistantly spaced about the periphery of said sleeve and an internal annular groove in said end portions opening to said slots whereby said terminal ends are received in said annular groove and portions of said wire lie in said slots.

5. The apparatus of claim 4 and further including slots in said body spaced apart a distance equal to the spacing between said terminal ends whereby said terminal ends may be inserted or removed from said annular 0 groove while said tubular sleeve is on said body.

6. A centralizer for use in a well bore comprising:

a cylindrical sleeve having slots formed through its wall on each end of said sleeve and internal annular recesses formed therein at each end adjacent the slots,

spring members having end portions at each end thereof for loosely positioning through the slots and into the annular recess, and

a housing member sized to be received within the bore of the cylindrical sleeve for maintaining said end portions of said spring members in said recesses,

said housing member having slots therein spaced for selectively registering with said end portions of said spring members.

7. The apparatus set forth in claim 6 with said sleeve being movable on saidvhousing for moving said end portions of said springs out of registration with said housing slots.

8. A centralizer for use in a well bore comprising:

an annular body with longitudinally-spaced openings peripherally arranged about the body,

springs tangentially projecting from said body, said springs having ends with an offset portion loosely received through said openings and positioned adjacent said annular body,

means spaced from and received within said annular body for holding said spring ends between said spaced means and said body to maintain the reception of said springs in said openings.

References Cited by the Examiner UNITED STATES PATENTS 2,248,160 7/41 Crawford 166241 2,717,650 9/55 Hall 166-241 2,826,253 3/58 Wright et al. 166-l72 2,881,840 4/59 Wright et a1. 166-175 3,072,196 1/63 Love 166241 BENJAMIN HERSH, Primary Examiner. CHARLES OCONNELL, Examiner, 

1. A CENTRALIZER FOR USE IN A WELL BORE COMPRISING A CYLINDRICAL SUPPORT MEMBER, SPRING MEMBERS INDIVIDUALLY HAVING A CONFIGURATION WHICH LIES IN A SINGLE PLANE AND HAVING ATTACHING PORTIONS FOR POSITIONING SAID SPRING MEMBERS ABOUT THE PERIPHERY OF SAID SUPPORT MEMBER, SAID ATTACHING PORTIONS BEING INTEGRALLY FORMED ON SAID SPRING MEMBERS FOR NORMALLY EXTENDING THE PLANES OF SAID SPRING MEMBERS TANGENTIALLY TO SAID SUPPORT MEMBER TO ACHIEVE CENTRALIZING FORCES BY A COMBINATION OF BENDING AND TORSION OF SAID SPRING MEMBERS, AND MEANS SPACED FROM SAID SUPPORT MEMBER FOR LOOSELY HOLDING SAID ATTACHING PORTIONS BETWEEN SAID SPACED MEANS AND SAID SUPPORT MEMBERS WITH SAID SPRING MEMBERS TANGENTIAL TO SAID SUPPORT MEMBER. 